Many systems have been proposed which can detect a signal from a sound source for a variety of different purposes. Videoconferencing systems and other communication systems, as well as various types of security, automation and monitoring systems are used to enhance, simplify or safeguard lives. More advanced sound-detecting systems also make it possible to determine the direction or location of the sound source using voice-directional camera image steering. In U.S. Pat. No. 5,778,082 to Chu et al., for example, a system and method for localization of an acoustic source is described using a pair of spatially separated microphones to obtain direction or location of speech or other acoustic signals from a common sound source. Similarly, U.S. Pat. No. 5,686,957 to Baker uses an array of microphones to determine the direction of a particular human speaker in a hemispheric viewing area, and to provide directional signals to a video camera system. However, since the Chu and Baker systems, as well as other similar systems can only detect the "differences" in audio signal amplitude, two or microphones must be used to determine directionality of a sound source, thus increasing the cost and complexity of these systems.
U.S. Pat. No. 5,742,693 to Elko discloses an acoustic transducer comprising a finite acoustical reflecting surface or baffle having one or more sensors to produce a first or second-order differential response pattern at a predetermined frequency. The sensors in Elko are image-derived sensors which must be positioned on the baffle itself. Furthermore, the transducer in Elko requires the baffle to be about one to one-half of an acoustic wavelength at a predetermined frequency. Such limitations make it difficult to use the device in Elko with standard videoconferencing equipment, such as video cameras.
For the reasons stated above, there is a need in the art for a more convenient and compact system for detecting the directionality of a sound source.